Illuminated signage employing light emitting diodes

ABSTRACT

An illuminated sign ( 88 ) includes a flexible electrical power cord ( 100 ) including first and second parallel conductors ( 112, 114 ) surroundingly contained within an insulating sheath defining a constant separation distance between the parallel conductors ( 112, 114 ). A plurality of light emitting diode (LED) devices ( 102 ) are affixed to the cord ( 100 ). Each LED device ( 102 ) includes an LED ( 104 ) having a positive lead ( 130   p ) electrically communicating with the first parallel conductor ( 112 ) and a negative lead ( 130   p ) electrically communicating with the second parallel conductor ( 114 ). A stencil ( 92 ) defines a selected shape, and the electrical cord ( 100 ) is arranged on the stencil ( 92 ). Power conditioning electronics ( 210, 220 ) disposed away from the stencil ( 92 ) electrically communicate with the first and second parallel conductors ( 112, 114 ) of the electrical power cord ( 100 ). The power conditioning electronics ( 210, 220 ) power the LED devices ( 102 ) via the parallel conductors ( 112, 114 ).

This application claims priority from U.S. Non-provisional patentapplication Ser. No. 09/866,581 filed on May 25, 2001 now U.S. Pat. No.6,660,935.

BACKGROUND OF THE INVENTION

Channel letters are known to those skilled in the art of makingcommercial signs as the most attractive and expensive form of signlettering. Briefly, channel letters usually include a plastic or metalbacking having the shape of the letter to be formed. Metal channelsiding, frequently formed of aluminum with a painted or otherwisefinished interior and exterior surface, is attached to and sealed to theletter backing, giving depth to the letter to be formed. Electricallighting fixtures, such as neon tubing and mounting brackets, areattached to the letter backing. Typically, a colored, translucentplastic letter face is attached to the front edge portion of the channelside material.

As discussed above, neon lighting is typically incorporated into channellettering systems. Neon systems are very fragile and, therefore, tend tofail and/or break during manufacture, shipping or installation. Also,such lighting systems use high voltage (e.g., between about 4,000 andabout 15,000 volts) electricity to excite the neon gas within thetubing. High voltage applications have been associated with deaths byelectrocution and building damage due to fire. Semiconductor lighting(e.g., light emitting diodes), that overcomes most of these drawbacks,has been used for channel lettering.

One such conventional channel lettering device attaches a light emittingdiode (“LED”) system to a back of a channel letter such that the LEDsystem emits light toward a translucent face at a front of the device.The LEDs are spaced at regular intervals (e.g., 2 inches) and arepressed into a socket. The socket is designed for a press-fit of amodified Super Flux (Piranha) package. The lead frames of the Piranhaare bent 90 degrees to fit into the socket. The connection for the LEDis similar to insulation displacement (“IDC”). The socket also has twoIDC places for a red and black wire. This system puts all of the LEDs inparallel. Furthermore, the two part power supply (Initial (120VAC to24VDC) and the Secondary (24VDC to ˜2.3VDC)) have two basic wiringconnections. The secondary has a sense circuit, which has one LEDattached for determining the voltage applied to the rest of the LEDsthat are attached to the second connection.

Another conventional channel lettering device attaches to a side of thechannel letter and is pointed toward the backing. The diffuse surface ofthe channel letter walls provides a uniform appearance. Each module hasa predetermined number of LEDs electrically connected in series.Furthermore, all of the modules are daisy chained together in a parallelcircuit. The LEDs are mounted on an aluminum base for heat sinkingpurposes.

Another conventional channel lettering device uses a plurality ofsurface mounted LEDs with an integral connector system.

Although these conventional LED channel lettering systems overcome someof the drawbacks associated with neon systems, other shortcomings areevident. For example, the conventional LED channel lettering systemsoffer only limited flexibility. More specifically, the LEDs cannot beeasily set into a desired shape involving significant curves or bends(e.g., wrapped around a pole or in a very small radius (<3 inches).Furthermore, the LEDs cannot be easily moved from one lightingapplication to another.

The present invention contemplates an improved apparatus and method thatovercomes the above-mentioned limitations and others.

BRIEF SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, anilluminated sign is disclosed. A flexible electrical power cord includesfirst and second parallel conductors surroundingly contained within aninsulating sheath defining a constant separation distance between theparallel conductors. A plurality of light emitting diode (LED) devicesare affixed to the cord. Each LED device includes an LED having apositive lead electrically communicating with the first parallelconductor and a negative lead electrically communicating with the secondparallel conductor. A stencil defines a selected shape and onto whichthe electrical cord is arranged. Power conditioning electronics disposedaway from the stencil electrically communicate with the first and secondparallel conductors of the electrical power cord. The power conditioningelectronics power the LED devices via the parallel conductors.

In accordance with another embodiment of the present invention, anarticle of manufacture is disclosed for installing a plurality of lightemitting diodes (LEDs) into a channel letter housing which has at leastone light-transmissive surface. A substantially rigid structure ispre-formed or formable for arrangement in the channel letter housing. Aflexible cable including at least two flexible parallel conductors isarranged to support an electrical potential difference between theparallel conductors. A plurality of LEDs electricallyparallel-interconnected by communication of the anode and cathode ofeach LED with the at least two conductors of the flexible cable. Afastener secures at least a portion of the flexible cable onto the rigidstructure. A power module receives power having first characteristicsand converts the received power to a supply power having secondcharacteristics which is communicated to the at least two conductors ofthe flexible cable to power the plurality of parallel-interconnectedLEDs.

In accordance with another embodiment of the present invention, a lightemitting diode (LED) light engine is disclosed. An electrical cableincludes at least two flexible electrical conductors. The electricalcable further includes a flexible, electrically insulating covering thatsurrounds the electrical conductors. The conductors are arrangedsubstantially parallel with a selected separation therebetween. An LEDwith a plurality of electrical leads separated by the selectedseparation electrically contacts the electrical conductors andmechanically pierces the insulating covering to mechanically secure theLED to the electrical cable.

In accordance with another embodiment of the present invention, a lightemitting diode (LED) light engine is disclosed. An electrical cableincludes a positive flexible conductor connected with an associatedpositive source of electrical power, a negative flexible conductorconnected with an associated negative source of electrical power, and anelectrically insulating covering surrounding and electrically insulatingthe positive and negative conductors and holding the conductors separateat a selected separation distance. An LED includes positive and negativeleads. A connector mechanically secures to the flexible insulatingcovering. The connector includes positive and negative prongs thatpierce the insulating covering and electrically contact the positive andnegative conductors, respectively. The connector further has the LEDmounted thereon with the positive and negative leads of the LEDelectrically contacting the positive and negative prongs, respectively.

In accordance with another embodiment of the present invention, a methodof manufacturing an LED light engine is provided. A plurality ofconductive elements are insulated to form a flexible electricallyinsulating conductor. An LED is mechanically secured to the insulatedconductive elements. Simultaneously with the mechanical securing, aplurality of leads of the LED are electrically contacted to respectiveones of the conductive elements.

In accordance with yet another embodiment of the present invention, aflexible lighting device is disclosed. A flexible cable includes anelectrically insulating sheath which contains positive and negativeconductors electrically isolated from one another. The sheath provides aspacing between the positive and negative conductors. A plurality oflight emitting diode (LED) devices are spaced apart from one another onthe cable. Each of the LED devices has an LED including positive andnegative leads mounted on a connector which mechanically secures the LEDdevice to a portion of the flexible cable and electrically connects thepositive and negative LED leads to the positive and negative conductorsthrough positive and negative conductive piercing members which piercethe sheath to make electrical contact with the respective conductors.

In accordance with still yet another embodiment of the presentinvention, a light emitting diode (LED) lighting apparatus is disclosed.A flexible electrical cable includes an anode wire and a cathode wirearranged in an electrically isolating sheath. A plurality of LED devicesare spaced apart along the cable and mechanically and electricallyconnect therewith. Each LED device includes an LED having at least oneanode lead and at least one cathode lead. Each LED device furtherincludes a connector with an LED socket that receives the anode andcathode leads. The LED socket mechanically retains the LED. Theconnector further includes a first electrically conductive path betweenthe anode lead and the anode wire, and a second electrically conductivepath between the cathode lead and the cathode wire. The first and secondconductive paths displace portions of the cable sheath.

One advantage of the present invention resides in providing a channellettering having a reduced number of parts compared with past systems.

Another advantage of the present invention resides in the use ofparallel interconnection of the LEDs which reduces the likelihood that afailed LED will adversely affect performance of other LEDs on the sameelectrical circuit.

Another advantage of the present invention resides in the locating ofthe conditioning electronics away from the channel lettering, e.g. in asecure and weatherproofed interior location.

Another advantage of the present invention is the avoidance of solderingconnections in the flexible LED light engine.

Yet another advantage of the present invention is that it allows forcoupling in the electrical power anywhere along the flexible LED lightengine.

Still yet another advantage of the present invention resides in itsmodular nature which allows part or all of a channel lettering to beconstructed on-site in a customized manner.

Numerous advantages and benefits of the present invention will becomeapparent to those of ordinary skill in the art upon reading andunderstanding the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may take form in various components and arrangements ofcomponents, and in various steps and arrangements of steps. The drawingsare only for purposes of illustrating a preferred embodiment and are notto be construed as limiting the invention.

FIG. 1 illustrates an LED light engine according to a first embodimentof the present invention.

FIG. 2 illustrates a perspective view of the LED shown in FIG. 1.

FIG. 3 illustrates an exploded view of an LED connector within a lightengine according to a second embodiment of the present invention.

FIG. 4 illustrates a cross-sectional view of the connector of the secondembodiment.

FIG. 5 illustrates a splice connector according to the presentinvention.

FIG. 6 illustrates an exploded view of the splice connector shown inFIG. 5.

FIG. 7 illustrates the light engine and the splice connector of thepresent invention used within a channel lettering system.

FIG. 8 illustrates an exploded perspective view of a suitable embodimentof a channel lettering system incorporating an intermediate stencil.

FIG. 9 illustrates a perspective view of a portion of the LED lightengine of FIG. 8 and its mounting to a portion of the stencil.

FIG. 10 illustrates an enlarged perspective view of one LED device ofFIG. 9 including a snap-on connector.

FIG. 11 illustrates an exploded perspective view of the LED device ofFIG. 10.

FIG. 12 illustrates the insulation-piercing members of the connector ofFIGS. 10 and 11, and their interconnection with the LED leads inside theconnector (connector body not shown in FIG. 12).

FIG. 13 illustrates the connecting of the insulation-piercing memberswith the conductors of the flexible electrical cable.

FIG. 14 illustrates an exploded view of the snap-on splice connector ofFIG. 9.

FIG. 15 illustrates a perspective view of an uncut stencil which issuitable for forming the shaped stencil of FIG. 8.

FIG. 16 illustrates a channel lettering with a suitable arrangement ofindependently adjustable power supply outputs.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, a light emitting diode (LED) light engine 10includes a flexible electrical conductor 12 surrounded by a flexible,electrically insulating covering 14. More specifically, the conductor 12includes a plurality of substantially parallel conductive elements 16,each of which is electrically insulated by the insulating covering 14.In the preferred embodiment, the insulating covering 14 includes rubber,PVC, silicone, and/or EPDM. However, other material are alsocontemplated.

Preferably, the conductor 12 includes two conductive elements 16 a, 16b. Furthermore, each of the conductive elements 16 a, 16 b is preferablysized to be about 14 gauge. Additionally, each of the conductiveelements 16 a, 16 b is preferably stranded and includes a plurality ofstrands 18 (e.g., seven strands).

The LED light engine 10 also includes an LED 20, which electricallycontacts the conductive elements 16 and is mechanically secured to theinsulating covering 14. More specifically, with reference to FIG. 2, theLED 20 includes a plurality of electrical leads 22 (e.g., one pair ortwo pairs of the leads 22). Although only one pair of the leads 22 a, 22b is necessary, additional pairs of the leads 22 c, 22 d offer addedstability to the LED 20 mounted on the conductor. Also, additional pairsof the leads 22 provide means for dissipating heat, thereby permittingmore current to be used for powering the LED 20. Each of the pairs ofleads 22 includes a first lead 22 a, 22 d, which connects, for example,to a negative electrical power source and a second lead 22 b, 22 c,which connects, for example, to a positive electrical power source. TheLED 20 typically a two-terminal device having an anode and a cathode. Ina suitable embodiment, the first lead 22 a, 22 d corresponds to theanode of the LED 20 and directly electrically connects to the conductiveelement 16 a, and the second lead 22 b, 22 c corresponds to the cathodeof the LED 20 and directly electrically connects to conductive element16 b.

With reference to FIGS. 1 and 2, the LED 20 is mechanically andelectrically secured to the conductor 12 by passing the leads 22 throughthe insulating covering 14 via an insulation displacement technique.Furthermore, after passing through the insulating covering 14, the leads22 contact the respective conductive elements 16. Preferably, the leads22 include tips that are wedge-shaped needles. The wedge-shaped needletips of the leads 22 pass between the strands 18 of the respectiveconductive elements 16 a, 16 b to form electrical contacts between theleads 22 and the conductive elements 16.

Preferably, the LED 20 is secured to the conductor 12 when the conductor12 is positioned flat (i.e., when the conductive elements 16 a, 16 b runin a common substantially horizontal plane which is above a horizontalsurface).

Optionally, the conductor 12 includes two dips (grooves) 24 a, 24 b inthe insulating covering 14. The dips 24 a, 24 b are positionedsubstantially above the respective conductive elements 16 a, 16 b,respectively. Before the LED 20 is secured to the conductor 12, theleads 22 are placed in the dips 24 a, 24 b and, therefore, aligned overthe conductive elements 16 a, 16 b, respectively. Then, after beingaligned in the dips 24, the leads 22 are passed through the insulatingcovering 14 and inserted into the conductive elements 16.

With reference to FIGS. 3 and 4, an alternate embodiment which includesa light engine 40 that secures an LED 50 to a conductor 52 via aconnector 54 is illustrated. The connector 54 includes first and secondsections 54 a, 54 b. The LED 50 is secured within the first section 54 abefore both of the sections 54 a, 54 b are secured (e.g., snapped orclamped) together. As in the first embodiment, the conductor 52 isflexible and includes a plurality of conductive elements 56 a, 56 b(e.g., two conductive elements) and an insulative covering electricallyisolating each of the conductive elements 56 a, 56 b. Furthermore, theconductive elements 56 a, 56 b are optionally stranded and include, forexample, seven strands 58.

Optionally, a hole 60 is formed in one of the sections 54 b throughwhich a means for securing (e.g., a fastener such as a screw, nail,bolt, etc.) is inserted for securing the connector 54 to a wall or othersupport means. For example, the connector 54 may be secured to a wall ofa channel lettering housing (see FIG. 7).

The connector section 54 b includes a plurality of electrical contacts62 that, once the sections 54 a, 54 b are snapped together, electricallycontact the LED 50. As is discussed below, the contacts 62, along withthe sections 54 a, 54 b, are used for mechanically securing theconnector 54 to the conductor 52. A plurality of pairs of the contacts62 electrically communicate with each other. More specifically, thecontacts 62 a, 62 c electrically communicate with each other while thecontacts 62 b, 62 d electrically communicate with each other. In asuitable embodiment, the electrical communication is a direct electricalcontacting, i.e. the contacts 62 a, 62 c are electrically continuous andthe contacts 62 b, 62 d are electrically continuous.

One set of the contacts 62 a, 62 c, for example, is electricallyconnected to a positive source of electrical power while the other setof the contacts 62 b, 62 d, for example, is electrically connected to anegative source of the electrical power. In this manner, the anode ofthe LED 50 is in direct electrical contact with the positive sourcewhile the cathode of the LED 50 is in direct electrical contact with thenegative source of electrical power. The set of contacts 62 a, 62 c iselectrically isolated from the set of contacts 62 b, 62 d. Furthermore,the electrical contacts 62 are V-shaped and sized to accept conductiveelements 56 a, 56 b within the respective V-shaped spaces. Morespecifically, the tips of the V-shaped electrical contacts 62 are sharpand formed for displacing (piercing) the insulative coverings around theconductive elements 56 a, 56 b.

Although only two of the contacts 62 a, 62 b (or, alternatively, 62 c,62 d) is necessary, the connector 54 preferably includes two pairs ofthe contacts 62 to offer added stability to the mechanical connectionbetween the connector 54 and the conductor 52.

After displacing the insulative coverings, the conductive elements 56 a,56 b are passed into the V-shaped spaces of the electrical contacts 62.As the conductive elements 56 a, 56 b are passed into the V-shapedspaces, the strands within the conductive elements 56 are wedged intothe vertex of the “V.” In this manner, a secure electrical contact ismade between the conductive elements 56 and the respective electricalcontacts 62. Furthermore, the strands are squeezed such that a shape ofthe conductor changes, for example, from round to oval. Also, as thestrands are squeezed, spaces between the strands is reduced such that anoverall size (e.g., diameter or circumference) of the respectiveconductive element 56 a, 56 b is reduced, for example, to a size of an“un-squeezed” three strand connector.

Preferably, the connector 54 is secured to the conductor 52 when theconductor 52 is positioned on-edge (i.e., when the conductive elements56 a, 56 b run in substantially parallel horizontal planes above asubstantially horizontal surface).

It is to be understood that although the embodiments have been describedwith reference to a single LED 20 (FIG. 1) and a single LED connector 54(FIG. 3) on the conductors 12, 52, respectively, a plurality of LEDs 20(FIG. 1) and LED connectors 54 (FIG. 3) on the conductors 12, 52,respectively, are contemplated so that the light engines 10, 40 formrespective LED strips. Furthermore, the LEDs 20 (FIG. 1) and LEDconnectors 54 (FIG. 3) on the conductors 12, 52 of the respective LEDlight strips 10, 40 are preferably spaced about two inches apart fromeach other. However, other spacings between the LEDs 20 and the LEDconnectors 54 are also contemplated.

Furthermore, if a plurality of the LEDs 20 are secured to the conductor12 (FIG. 1), which is oriented in a flat position, the conductor 12 isflexible in a first direction. However, if a plurality of the connectors54 are secured to the conductor 52 (FIG. 3), which is oriented in anon-edge position, the conductor 52 is flexible in a second direction.

With reference to FIGS. 5 and 6, a splice connector 70 mechanically andelectrically connects a plurality of flexible conductors (e.g., twoconductors) 72, 74 together. Like the connector 54 (see FIG. 3), thesplice connector 70 includes a plurality of portions (e.g., twoportions) 70 a, 70 b. Preferably, the portions 70 a, 70 b are slidablyinterconnected to each other. Furthermore, the portions 70 a, 70 b slidebetween two positions (e.g., an open position and a closed position). Inthe closed position, the portions 70 a, 70 b are secured together vialocking tabs 71, which engage mating tabs 73. Although only one lockingtab 71 and one mating tab 73 is shown in FIG. 6, it is to be understoodthat additional locking and mating tabs are also contemplated.Furthermore, like the conductor 52 and the connector 54 of FIG. 3, thesplice connector 70 of FIGS. 5 and 6 is preferably secured to theconductors 72 (shown), 74 (not shown) when the conductors 72, 74 areoriented in an on-edge position. Also, the splice connector 70 includesa plurality of electrical contacts 76 (e.g., two electrical contacts),which are preferably V-shaped and function in a similar manner to thecontacts 62 shown in FIG. 4. In the closed position, the locking tabs 71are secured by the mating tabs 73 such that the conductors 72, 74 aresecured within the V-shaped contacts 76.

The conductors 72, 74 are aligned parallel and on-edge with respect toone another. Then, the splice connector 70 is secured around both of theconductors 72, 74. In this manner, respective first conductive elements72 a, 74 a are mechanically and electrically secured to one another;similarly, respective second conductive elements 72 b, 74 b aremechanically and electrically secured to one another.

With respect to FIG. 7, a channel lettering system 80 includes LEDs 82mechanically and electrically connected to flexible conductors 84according to the present invention. It is to be understood that the LEDs82 are either directly connected to the conductors 84 (as shown inFIG. 1) or connected to the conductors 84 via connectors 54 (as shown inFIG. 3). Furthermore, the splice connector 70 is shown mechanically andelectrically connecting the conductor 84 to an additional conductor 86.

With reference to FIGS. 8–16, yet another suitable embodiment of anilluminated sign or channel lettering 88 is described. As shown in FIG.8, a flexible light engine 90 is mounted on a stencil 92 which defines aselected shape, e.g. the capital letter “E”, which conforms with ahousing 94 also conforming to the letter “E” and including at least atranslucent surface 96 arranged to pass light generated by thecurvilinear LED light source 90. The stencil 92 is shaped forarrangement in the housing 94.

With continuing reference to FIG. 8 and with further reference to FIG.9, the flexible light engine 90 includes an insulated flexibleelectrical cord 100 on which a plurality of LED devices 102 are disposedin a spaced apart manner. Each LED device 102 includes an LED 104 with alead frame which is affixed in a first region 106 of a connector 108.The connector 108 also includes a second region 110 that clamps onto thecord 100. The second region 110 includes a snap-type connector similarto that previously described with reference to FIGS. 3 and 4, andsimilarly serves to connect the LED 104 with parallel electricalconductors 112, 114 of the cord 100. As shown in FIG. 9, the conductors112, 114 are maintained at an essentially constant separation by aninsulating sheath 115 of the cord 100, and so the clamping connectors108 can be placed anywhere along the cord 100.

Because the LED devices 102 are spaced apart along the flexibleelectrical cable 100, for example at two-inch spacings, the interveningcable portions between the LED devices 102 can bend to define a channelletter shape or other selected pattern, such as the letter “E” formed bythe light engine 90 in FIG. 8. In the embodiment of FIGS. 8–16, it willbe appreciated that the two parallel electrical conductors 112, 114within the insulating sheath 115 of the cord 100 define a spatiallylocalized cable plane containing the two conductors 112, 114. The cable100 is bendable in a direction out of the local cable plane, whoseorientation varies with the bending of the cable 100, but is relativelyinflexible in the local cable plane, since bending within the localcable plane produces compressive and tensile forces along the axes ofthe conductors 112, 114. Hence, the cable 100 is bendable in the planeof the stencil 92 to form the light engine 90 into a pattern on thestencil 92. Note that the plane of the stencil 92 is everywhereperpendicular to the local cable plane as the cable is bent to conformwith a selected lettering. It will also be recognized that the LEDdevices 102 are oriented such that illumination produced by the LEDs 104is substantially directed parallel to the local cable plane, i.e.perpendicular to the plane of the stencil 92, so that the LED devices102 produce illumination directed away from the stencil 92.

The second region 110 advantageously employs a mechanical connectionwhich also effectuates the electrical connections of the LED 104 to theconductors 112, 114 in a manner similar to that described previously,e.g. using electrical leads 62 (see FIGS. 3 and 4) that penetrate theelectrical insulation 115 of the cord 100 during the mechanical snapconnection. Optionally, the second region 110 supports detachableattachment, such as an un-snapping removal of the connector 108 from thecord 100. Although such detachment can leave small openings where theinsulation 115 has been displaced, the potential difference appliedacross the LED devices 102 in the parallel interconnection is typicallylow, such as a few volts corresponding to typical optimal forwardvoltages for commercial LEDs, and so significant safety hazards are notpresented by the degraded insulation.

With continuing reference to FIGS. 9 and 10, each connector 108additionally includes a third region 116 adapted to cooperate with afastener 118 for securing the connector 108 to the stencil 92. In theillustrated embodiment, the third region 116 includes a slot 120 thatreceives the fastener 118, which in the illustrated embodiment is anexemplary threaded screw. The fastener 118 shaft passes through the slot120 and threads into one of a plurality of openings 122 arranged in thestencil 92.

With particular reference to FIG. 9, the cable 100 includes two lengthsof cable 100 ₁, 100 ₂ that are spliced together using a snap-on spliceconnector 124, which is described later in greater detail with referenceto FIG. 14. The splice connector electrically connects the conductors112 of the two cables 100 ₁, 100 ₂ to form one continuous conductor, andalso electrically connects the conductors 114 of the two cables 100 ₁,100 ₂ to form another continuous conductor. The combined conductors 112,114 are electrically isolated from one another by the insulating coatingor sheath 115. Additionally, FIG. 9 shows a power connector 126 whichconnects with the cord 100 using the same type of snap-on clamp as isemployed by the second region 110 of the connector 108. The exemplarypower connector 126 includes receptacles 128 adapted to connect withprongs of a power cable connector (not shown). Although the powerconnector 126 is shown connected near an end of the curvilinear LEDlight source 90, it will be appreciated that due to the parallelelectrical configuration of the source 90 the power connector 126 caninstead be arranged essentially anywhere along the source 90, includingbetween LED devices 102. Indeed, the choice of where to clamp the powerconnector 122 onto the curvilinear LED light source 90 is preferablydetermined by the geometry of the illuminated sign 88 and by thelocation of the driving power source (see FIG. 16). Optionally, thepower connector can be integrated into a splice connector or into an LEDconnector.

With particular reference to FIGS. 11 and 12, assembly of an exemplaryLED device 102 is described. The LED 104 includes leads 130,specifically two positive leads 130 _(P) electrically communicating withthe positive terminal or anode of the LED 104, and two negative leads130 _(N) (one of which is blocked from view in FIGS. 11 and 12)electrically communicating with the negative terminal or cathode of theLED 104. The LED 104 also preferably includes a light-transmissiveencapsulant 132 encapsulating a semiconductor chip or otherelectroluminescent element (not shown). The encapsulant 132 isoptionally formed into a lens or other selected light-refractive shape.Furthermore, the encapsulant 132 optionally includes a phosphorescentmaterial, a tinting, or the like that changes or adjusts the spectraloutput of the LED 104. Those skilled in the art will recognize that theLED 104 is substantially similar to commercially available LED packages,such as the P4 (piranha) LED package.

The first region 106 includes a socket that receives the LED 104 withthe light-emitting surface (i.e., the surface with the encapsulant 132disposed thereon) facing away from the connector 108 and the LED leads130 inserting into the socket. The connector 108 includes a firstsection 140 with the first region 106 that provides the LED mount orsocket, and a second section 142 that connects with the first section140 in a clamping or snapping fashion. The second region 110 includingthe clamp, mechanical snap connection, or the like is defined by theconnection of the two sections 140, 142 about a portion of the flexibleelectrical cable 100.

With continuing reference to FIGS. 11 and 12, the first section 140 alsoincludes positive and negative conductive insulation-piercing members orprongs 144 _(P), 144 _(N) that are arranged in a substantially fixedmanner in slots or openings (not shown) of the first section 140 of theconnector 108. Each prong 144 is substantially planar and includes slots146 that compressively receive the corresponding (positive or negative)LED leads 130 to effectuate electrical contact of the positive andnegative terminals (anode and cathode) of the LED with the correspondingpositive or negative prong 144 _(P), 144 _(N). The receiving of the LEDleads 130 into the slots 146 is compressive and does not include asoldering step. Hence, it is contemplated that the LED 104 is optionallydetachable from the socket region 106 of the first section 140, forexample to facilitate replacement of a failed LED 104.

Assembly of the first section 140 of the connector 108 includesinserting the prongs 144 _(P), 144 _(N) into the first section 140, andinserting the LED 104 into the socket of the first region 106 so thatthe LED leads 130 compressively fit into the slots 146 of the prongs 144to effectuate electrical contact therewith. In a preferred embodiment,the first section 140 is a molded body of plastic or anotherelectrically insulating material, the prongs 144 are formed from sheetmetal or another substantially planar electrically conductive material,and the LED 104 is a pre-packaged LED of a type known to the art, e.g.an electroluminescent semiconducting element arranged in a P4 (piranha)package with suitable epoxy or other encapsulant. It will be appreciatedthat a significant advantage of the connectorized LED device 102 is thatassembly thereof involves no soldering steps.

With continuing reference to FIGS. 11 and 12, and with further referenceto FIG. 13, each prong 144 includes a “V”-shaped or bifurcated end 148that extends out of the first section 140 toward the second section 142such that when the first and second sections 140, 142 are clamped orsnapped together with the cable 100 arranged therebetween the ends 148of the prongs 144 puncture the cable insulation 115 and contact theconductors 112, 114. Each bifurcated end 148 defines a gap 150 sized toreceive the respective conductor 112, 114 of the flexible electricalcable 100. As best seen in FIG. 13, each conductor 112, 114 is amulti-stranded conductor which compressively squeezes into the gap 150of one of the prongs 144 _(P), 144 _(N) when the two connector sections140, 142 are clamped or snapped about the cable 100. The compressionpreferably does not break or fracture the individual strands of theconductors 112, 114, but does ensure a reliable electrical contactbetween the prongs 144 _(P), 144 _(N) and the respective conductors 112,114.

It will be appreciated that the snapping connection of the first andsecond sections 140, 142 about the cable 100 effectuates both amechanical connection of the LED device 102 to the cable 100 as well asa simultaneous electrical connection of the positive and negative (anodeand cathode) terminals of the LED 104 via the prongs 144 _(P), 144 _(N)to the conductors 112, 114 that supply electrical power. The electricalconnection does not include auxiliary electrical components, such asresistors or the like, and does not include soldering. Hence the LEDdevice 102 includes few component parts in the channel lettering whichreduces the likelihood of device failure. However, it is alsocontemplated to include resistive or other circuit elements in theconnector 108 to perform selected power conditioning or other electricaloperations.

Preferably, the conductors 112, 114, the prongs 144 _(P), 144 _(N), andthe LED leads 130 are formed from substantially similar metals to reducegalvanic corrosion at the electrically contacting interfaces, or arecoated with a conductive coating that reduces galvanic corrosion at theinterfaces. In a suitable embodiment, the conductors 112, 114, theprongs 144 _(P), 144 _(N), and the LED leads 130 are each coated with aconductive coating of the same type, which ensures that galvaniccorrosion at the contacting surfaces is minimized. Particularly in thecase of high power LED devices 102, embodiments that employed contactingsurfaces with mismatched compositions typically experienced significantdetrimental galvanic corrosion at the contacting surfaces.

With reference to FIGS. 10 and 11, the first connector section 140includes a clip 154 that cooperates with a recess or receiving region156 of the second connector section 142 to snappingly secure the firstand second sections 140, 142 together onto the cable 100, as shown inthe secured position in FIG. 10. In the embodiment illustrated in FIGS.10 and 11, the first connector section 140 further includes features 157that mate with grooves 158 of the second connector section 142 to definea tongue-and-groove sliding engagement. The tongue-and-groove slidingengagement facilitates correct alignment of the tips of the prongs 148_(P), 148 _(N)respective to the second connector section 142 and thecable 100 when the first and second connector sections 140, 142 aresnapped together, and together with the clip 154 mating into thereceiving region 156 secures the connector 108 to the cable 100 withoutpiercing the cable except by the prongs 144 _(P), 144 _(N). Of course,other securing mechanisms can also be employed.

With reference to FIG. 9 and with further reference to FIG. 14, thesplice connector 124 employs a similar simultaneouselectrical/mechanical connection of the splice connector 124 to cables100 ₁, 100 ₂ to splice the cables 100 ₁, 100 ₂ together. The spliceconnector 124 includes three sections 160, 162, 164, which arepreferably formed of a molded plastic or other insulating material. Thesection 162 is a middle section that includes positive and negativedouble-ended insulation-piercing elements or prongs 166 _(P), 166 _(N)that insert into slots 168 _(P), 168 _(N) of the section 162 in asubstantially rigid manner similar to the inserting of the prongs 144_(P), 144 _(N) into the section 140 of the connector 108 of the LEDdevices 102. The prongs 166 _(P), 166 _(N) preferably include bifurcatedends 150 as with the prongs 144 _(P), 144 _(N) of the LED devices 102,which are sized to squeeze the multi-stranded conductors 112, 114without fracturing conductor strands.

With continuing reference to FIGS. 9 and 14, the sections 160, 162 ofthe splice connector 124 mechanically snap onto the flexible electricalcable 100 ₂. The snapping together causes the prong ends 150 ₁, 150 ₂ topierce the insulation 115 and connect with the conductors 112, 114,respectively, of the cable 100 ₂. The snapping connection includesengagement of a clip 170 of the connector section 162 with a recess 172of the connector section 160 to secure the sections 160, 162 about thecable 100 ₂. Similarly, the sections 162, 164 of the splice connector124 mechanically snap onto the flexible electrical cable 100 ₁ withprong ends 150 ₃, 150 ₄ piercing the insulation 115 and connecting withthe conductors 112, 114, respectively, of the cable 100 ₁. The snappingconnection includes engagement of a clip 174 of the connector section162 with a recess 176 of the connector section 164 to secure thesections 162, 164 about the cable 100 ₁. Hence, the prong 166 _(P)provides electrical connection between the conductors 112 of the cables100 ₁, 100 ₂, while the prong 166 _(N) provides electrical connectionbetween the conductors 114 of the cables 100 ₁, 100 ₂, to electricallyconnect the cables during the mechanical connecting of the cables 100 ₁,100 ₂ by the splice connector 124.

With reference to FIGS. 8 and 9 and with further reference to FIG. 15,construction of the exemplary illuminated sign 88 is advantageouslymodular and selectably divided between the manufacturer and the enduser. In one suitable embodiment, the LEDs 104 are installed on theconnectors 108 to form the LED devices 102, and the LED devices 102 aresnapped onto the flexible cable 100 at the factory to form themanufactured flexible light engine 90. A stencil board 180 shown in FIG.15 includes pre-formed openings 122, and can be cut at the installationsite to match the selected letter housing 94, e.g. the stencil board 130is cut to form the exemplary “E”-shaped stencil 92. Suitable lengths ofthe flexible LED light source 90 are cut off and affixed on the shapedstencil 92 using the third regions 116 of the connectors 108 andfasteners 118 applied to selected pre-formed openings 122. Splices 124are applied as appropriate, and the power connector 126 is snapped ontothe cord 100 at a selected convenient point. Optionally, the pre-formedopenings 122 are omitted, and the fasteners 118 displace the stencilmaterial to fasten thereto. For example, the displacing fasteners can bewood screws with sharp tips for engaging and penetrating the stencilmaterial.

In a variation of the above installation process, the LEDs 104 areinstalled on the connectors 108 at the factory, but the LED devices 102are snapped onto the cable 100 at selected locations along the cable 100at the installation site. This approach is more labor-intensive at theinstallation site, but provides maximum flexibility in the selection andspacing of the LED devices 102 along the cord 100. Such a modular systemcan allow the end-user to select the colors of the LEDs 104 to create acustom multi-color flexible LED light source 90.

In yet another variation, the connector 108 is optionally omittedsimilarly to the previously-described embodiment of FIGS. 1 and 2, andthe LED leads 130 _(P), 130 _(N) directly affixed to the cord 100. Anyof the above installation/assembly processes are particularly suitablefor retro-fitting an existing channel lettering. The shaped stencil 92advantageously allows the light source 90 to be routed around or overobstructions or features such as cross-members within the existingchannel letter.

With continuing reference to FIGS. 8–15, and with further reference toFIG. 16, a channel lettering 200 that displays “TEXT” is shown. Thechannel lettering portion “TE” is powered by a first power supply 210which includes two power output lines 212, 214. The channel letteringportion “XT” is powered by a second power supply 220 which includes twopower output lines 222, 224.

Each power supply 210, 220 is arranged away from the illuminated channellettering “TEXT”, for example in the interior of an associated building,and includes conditioning electronics for converting building power(e.g., 120V a.c. in the United States, or 220V a.c. in Europe) to powersuitable for driving the LED light sources of the channel lettering.Since a parallel electrical connection is used in the light engine 90,the output power is low voltage, corresponding to the driving voltage ofa single LED, and so a low voltage power supply can be employed. In apreferred embodiment, the power supplies 210, 220 are class II powersupplies which have output power limited to 5 amperes and 30 volts.Class II power supplies are relatively safe due to the low voltages andcurrents produced thereby, and the output lines 212, 214, 222, 224 aretypically not required by electrical codes to be arranged in safetyconduits.

Of course, each power supply can include a different number of poweroutput lines, e.g. one, three, or more power output lines. Each poweroutput line provides a selectable electrical output power, for exampleas monitored by the meters 226. In a preferred embodiment, the powerdelivered to each power output line is individually controllable using aknob 228 or other control input. This permits balancing the lightintensity of the letters, e.g. of the letters “T”, “E”, “X”, and “T”, toobtain a uniformly lit sign “TEXT”.

FIG. 16 also schematically shows the use of a splice connector 230, suchas the splice connector 124 of FIG. 14, to connect the upper and lowercable lengths 232, 234 of the “X” channel letter. Note that thissplicing is arranged in the middle of each of the two flexibleelectrical cable lengths 232, 234. It will be appreciated that thesplice connector can be connected substantially anywhere along thelength of an electrical cable to provide great flexibility in cablearrangement.

The invention has been described with reference to the preferredembodiments. Obviously, modifications and alterations will occur toothers upon reading and understanding the preceding detaileddescription. It is intended that the invention be construed as includingall such modifications and alterations insofar as they come within thescope of the appended claims or the equivalents thereof.

1. An illuminated sign comprising: a channel letter housing defining atleast one channel; and a flexible lighting strip secured within thechannel of the channel letter housing, the flexible lighting stripincluding: a flexible electrical power cord including spaced apartparallel conductors in an insulating sheath, a plurality of LEDs, and aplurality of connectors each supporting at least one LED, the connectorsbeing spaced apart along the flexible electrical power cord andconnected therewith, each connector including prongs that pierce theinsulating sheath to connect with conductors of the flexible power cordto deliver electrical power from the flexible electrical power cord tothe at least one LED, each connector further including first and secondconnector sections that are secured about a portion of the flexibleelectrical power cord to secure the connector thereto, the first andsecond connector sections including mating connector section securingfeatures disposed on opposite sides of the flexible electrical powercord for securing the first and second connector sections about theportion of the flexible electrical power cord, the mating connectorsection securing features including a tongue-and-groove slidingengagement between the first and second connector sections disposed atone side of the flexible electrical power cord.
 2. The illuminated signas set forth in claim 1, wherein the prongs deliver electrical powerfrom the flexible electrical power cord to the at least one LED via oneof (i) direct connection with leads of the LED or (ii) one or morecircuit elements.
 3. An illuminated sign comprising: a channel letterhousing defining at least one channel; and a flexible lighting stripsecured within the channel of the channel letter housing, the flexiblelighting strip including: a flexible electrical power cord includingspaced apart parallel conductors in an insulating sheath, the spacedapart parallel conductors in the insulating sheath defining a cord planearranged transverse to a surface of the channel to which the flexiblelighting strip is secured, a plurality of LEDs, and a plurality ofconnectors each supporting at least one LED, the connectors being spacedapart along the flexible electrical power cord and connected therewith,each connector including prongs that pierce the insulating sheath toconnect with conductors of the flexible power cord to deliver electricalpower from the flexible electrical power cord to the at least one LED.4. The illuminated sign as set forth in claim 3, further comprising: astencil conforming with the at least one channel of the channel letterhousing and secured within the at least one channel, the flexiblelighting strip being secured to the stencil.
 5. The illuminated sign asset forth in claim 4, wherein each connector includes: a bracket bywhich the connector is secured to the stencil.
 6. The illuminated signas set forth in claim 3, wherein each connector of the flexible lightingstrip comprises: first and second connector sections that are securedabout a portion of the flexible electrical power cord to secure theconnector thereto.
 7. The illuminated sign as set forth in claim 6,wherein the first and second connector sections comprise: matingconnector section securing features disposed on opposite sides of theflexible electrical power cord for securing the first and secondconnector sections about the portion of the flexible electrical powercord.
 8. The illuminated sign as set forth in claim 7, wherein themating connector section securing features comprise: a clip disposed onthe first connector section at one side of the flexible electrical powercord that mates with a receiving region of the second connector sectionat the same side of the flexible electrical power cord.
 9. Theilluminated sign as set forth in claim 3, wherein each connector of theflexible lighting strip comprises: first and second connector sectionsthat are secured about a portion of the flexible electrical power cordto secure the connector thereto, the at least one LED being supported onone of the first and second connector sections in a position outside ofthe cord plane.
 10. The illuminated sign as set forth in claim 3,wherein the connectors do not pierce the flexible lighting strip exceptvia the prongs.
 11. The illuminated sign as set forth in claim 3,wherein the conductors of the flexible power cord do not includeelectrical discontinuities.
 12. The illuminated sign as set forth inclaim 3, wherein the at least one LED supported by each connector isarranged on the connector spatially offset from the cord plane.
 13. Theilluminated sign as set forth in claim 3, further comprising: a powersupply disposed outside of the channel letter housing for deliveringpower to the flexible electrical power cord of the flexible lightingstrip.
 14. The illuminated sign as set forth in claim 13, wherein thepower supply is a class II power supply.
 15. The illuminated sign as setforth in claim 3, wherein the prongs deliver electrical power from theflexible electrical power cord to the at least one LED via one of (i)direct connection with leads of the LED or (ii) one or more circuitelements.
 16. The illuminated sign as set forth in claim 3, wherein eachprong has a bifurcated tip that receives one of the parallel conductorsof the flexible electrical power cord.
 17. The illuminated sign as setforth in claim 3, wherein interfacing surfaces of the parallelconductors and the prongs are made of substantially similar metals toreduce galvanic corrosion.
 18. The illuminated sign as set forth inclaim 3, wherein interfacing surfaces of the parallel conductors and theprongs include a conductive coating that reduces galvanic corrosion atthe interfaces.
 19. An illuminated sign comprising: a channel letterhousing defining at least one channel; a flexible lighting strip securedwithin the channel of the channel letter housing, the flexible lightingstrip including: a flexible lighting strip including at least two stripbranches defined by two flexible electrical power cords each includingspaced apart parallel conductors in an insulating sheath, a plurality ofLEDs, and a plurality of connectors each supporting at least one LED,the connectors being spaced apart along the flexible electrical powercord and connected therewith, each connector including prongs thatpierce the insulating sheath to connect with conductors of the flexiblepower cord to deliver electrical power from the flexible electricalpower cord to the at least one LED; a power supply disposed outside ofthe channel letter housing for delivering power to the flexible lightingstrip; and a splice connector electrically connecting the two flexibleelectrical power cords of the flexible lighting strip.
 20. Theilluminated sign as set forth in claim 19, wherein one of the twoflexible electrical power cords is electrically connected with the powersupply, and the other of the two flexible electrical power cordsreceives electrical power from the splice connector.
 21. The illuminatedsign as set forth in claim 19, wherein the power supply electricallyconnects with the splice connector to deliver electrical power to thetwo flexible electrical power cords.
 22. An illuminated sign comprising:a channel letter housing defining at least one channel; a flexiblelighting strip secured within the channel of the channel letter housing,the flexible lighting strip including: a flexible electrical power cordincluding spaced apart parallel conductors in an insulating sheath, aplurality of LEDs, and a plurality of connectors each supporting atleast one LED, the connectors being spaced apart along the flexibleelectrical power cord and connected therewith, each connector includingprongs that pierce the insulating sheath to connect with conductors ofthe flexible power cord to deliver electrical power from the flexibleelectrical power cord to the at least one LED; a power supply disposedoutside of the channel letter housing for delivering power to theflexible electrical power cord of the flexible lighting strip; and apower connector by which the power supply is connected with the flexibleelectrical power cord, the power connector being arranged between two ofthe connectors that are spaced apart along the flexible electrical powercord.
 23. An illuminated sign comprising: a channel letter housingdefining at least one channel; a flexible lighting strip secured withinthe channel of the channel letter housing, the flexible lighting stripincluding: a flexible electrical power cord including two or more endsand including spaced apart parallel conductors in an insulating sheath,a plurality of LEDs, and a plurality of connectors each supporting atleast one LED, the connectors being spaced apart along the flexibleelectrical power cord and connected therewith, each connector includingprongs that pierce the insulating sheath to connect with conductors ofthe flexible power cord to deliver electrical power from the flexibleelectrical power cord to the at least one LED; a power supply disposedoutside of the channel letter housing for delivering power to theflexible electrical power cord of the flexible lighting strip; and apower connector by which the power supply is connected with the flexibleelectrical power cord, the power connector being connected with theflexible electrical power cord at a point away from any of the two ormore ends of the flexible electrical power cord.
 24. An illuminated signcomprising: a channel letter housing defining at least one channel; anda flexible lighting strip secured within the channel of the channelletter housing, the flexible lighting strip including: a flexibleelectrical power cord including spaced apart parallel conductors in aninsulating sheath, a plurality of LEDs, and a plurality of connectorseach supporting at least one LED, the connectors being spaced apartalong the flexible electrical power cord and connected therewith, eachconnector including prongs that pierce the insulating sheath to connectwith conductors of the flexible power cord to deliver electrical powerfrom the flexible electrical power cord to the at least one LED, eachprong having a bifurcated tip that receives one of the parallelconductors of the flexible electrical power cord, the parallelconductors being multi-stranded conductors that are compressively heldwithin the bifurcated ends of the prongs.
 25. The illuminated sign asset forth in claim 24, wherein each connector of the flexible lightingstrip comprises: first and second connector sections that are securedabout a portion of the flexible electrical power cord to secure theconnector thereto.
 26. The illuminated sign as set forth in claim 25,wherein the first and second connector sections comprise: matingconnector section securing features disposed on opposite sides of theflexible electrical power cord, for securing the first and secondconnector sections about the portion of the flexible electrical powercord.
 27. The illuminated sign as set forth in claim 24, wherein theconnectors do not pierce the flexible lighting strip except via theprongs.
 28. The illuminated sign as set forth in claim 24, wherein theconductors of the flexible power cord do not include electricaldiscontinuities.
 29. The illuminated sign as set forth in claim 24,wherein the at least one LED supported by each connector is arranged onthe connector spatially offset from the cord plane.
 30. The illuminatedsign as set forth in claim 24, wherein the prongs deliver electricalpower from the flexible electrical power cord to the at least one LEDvia one of (i) direct connection with leads of the LED or (ii) one ormore circuit elements.
 31. The illuminated sign as set forth in claim24, wherein interfacing surfaces of the parallel conductors and theprongs are made of substantially similar metals to reduce galvaniccorrosion.
 32. The illuminated sign as set forth in claim 24, whereininterfacing surfaces of the parallel conductors and the prongs include aconductive coating that reduces galvanic corrosion at the interfaces.33. An illuminated sign comprising: a channel letter housing defining atleast one channel at least a portion of which is curved; and a flexiblelighting strip secured within the channel of the channel letter housing,at least a portion of the flexible lighting strip being secured in acurved configuration conforming with the at least one curved channelportion, the flexible lighting strip including: a flexible electricalpower cord including spaced apart parallel conductors in an insulatingsheath, the spaced apart parallel conductors in the insulating sheathdefining a cord plane arranged transverse to a surface of the channel towhich the flexible lighting strip is secured, a plurality of LEDs, and aplurality of connectors each supporting at least one LED, the connectorsbeing spaced apart along the flexible electrical power cord andconnected therewith, each connector including prongs that pierce theinsulating sheath to connect with conductors of the flexible power cordto deliver electrical power from the flexible electrical power cord tothe at least one LED.
 34. The illuminated sign as set forth in claim 33,wherein each connector of the flexible lighting strip comprises: firstand second connector sections that are secured about a portion of theflexible electrical power cord to secure the connector thereto.
 35. Theilluminated sign as set forth in claim 34, wherein the first and secondconnector sections comprise: mating connector section securing featuresdisposed on opposite sides of the flexible electrical power cord forsecuring the first and second connector sections about the portion ofthe flexible electrical power cord.
 36. The illuminated sign as setforth in claim 33, wherein the connectors do not pierce the flexiblelighting strip except via the prongs.
 37. The illuminated sign as setforth in claim 33, wherein the conductors of the flexible power cord donot include electrical discontinuities.
 38. The illuminated sign as setforth in claim 33, wherein the at least one LED supported by eachconnector is arranged on the connector spatially offset from the cordplane.
 39. The illuminated sign as set forth in claim 33, wherein theprongs deliver electrical power from the flexible electrical power cordto the at least one LED via one of (i) direct connection with leads ofthe LED or (ii) one or more circuit elements.
 40. The illuminated signas set forth in claim 33, wherein interfacing surfaces of the parallelconductors and the prongs are made of substantially similar metals toreduce galvanic corrosion.
 41. The illuminated sign as set forth inclaim 33, wherein interfacing surfaces of the parallel conductors andthe prongs include a conductive coating that reduces galvanic corrosionat the interfaces.